Application Of Laser Welding Machine In The Field Of Lithium Battery
The battery's explosion-proof valve is a thin-walled valve body located on the battery sealing plate. It serves the critical function of rupturing when the internal pressure of the battery surpasses the specified threshold, preventing the battery from bursting.
As the backbone of new energy vehicles, the power battery's quality profoundly influences the overall vehicle performance. Lithium battery manufacturing equipment is typically categorized into three types: front-end equipment, mid-end equipment, and back-end equipment. The precision and automation level of this equipment directly impact production efficiency and product consistency. Laser processing technology has emerged as a popular alternative to traditional welding methods in lithium battery manufacturing equipment, offering enhanced precision and efficiency.
Welding plays a crucial role in the manufacturing process of lithium batteries, spanning from cell production to battery pack assembly. The conductivity, strength, airtightness, resistance to metal fatigue, and corrosion resistance are key criteria used to assess the quality of battery welding. The choice of welding method and process significantly impacts the cost, quality, safety, and consistency of the batteries.
Battery Explosion-proof Valve Welding
The battery's explosion-proof valve is a thin-walled valve body located on the battery sealing plate. It serves the critical function of rupturing when the internal pressure of the battery surpasses the specified threshold, preventing the battery from bursting. Due to its ingenious structure, this process imposes stringent requirements on the laser welding procedure.
Previously, pulsed laser welding was employed for battery explosion-proof valve welding. However, this method had limitations, with low welding efficiency and relatively poor sealing performance. Continuous laser welding has since emerged as a superior alternative, enabling high-speed and high-quality welding. It ensures welding stability, efficiency, and yield, thereby enhancing overall performance and safety.
Battery Tab Welding
Battery tabs typically consist of three materials. The positive electrode of the battery utilizes aluminum material, while the negative electrode employs nickel material or copper nickel-plated material. During the manufacturing process of power batteries, one crucial step involves welding the battery tabs to the poles. In the production of secondary batteries, it is necessary to weld them with another aluminum safety valve. Welding is essential not only to ensure a secure connection between the tab and the pole but also to achieve a smooth and aesthetically pleasing weld seam.
Spot Welding of Battery Poles
Battery pole strips are typically fabricated from various materials, including pure aluminum strips, nickel strips, aluminum-nickel composite strips, and a small amount of copper strips. The welding process for battery strips commonly utilizes pulse welding machines. However, with the introduction of IPG's QCW quasi-continuous laser, it has become increasingly prevalent in battery strip welding applications. This laser technology offers advantages such as good beam quality and the ability to create small welding spots, making it particularly suitable for welding aluminum strips, copper strips, and narrow-band battery poles with high reflectivity.
Seal Welding of Power Battery Shell and Cover Plate
Seal welding of power battery shells are typically composed of aluminum alloy or stainless steel, with aluminum alloy being the most commonly used material, often 3003 aluminum alloy or occasionally pure aluminum. Stainless steel is highly weldable using lasers, and both pulsed and continuous lasers can generate welds that exhibit excellent appearance and performance.
The utilization of continuous lasers for welding thin-shell lithium batteries can significantly enhance efficiency, boosting it by 5 to 10 times while also improving appearance and sealing performance. Consequently, there is a noticeable trend towards gradually replacing pulsed lasers in this application field.
Power Battery Module and Pack Welding
The series-parallel connection of power batteries typically involves welding the connecting piece to the individual battery. Given that the positive and negative electrodes are crafted from different materials, namely copper and aluminum, a unique challenge arises. Laser welding copper and aluminum results in the formation of brittle compounds, rendering them unsuitable for use. Therefore, laser welding is typically reserved for copper-to-copper and aluminum-to-aluminum connections. Alternatively, ultrasonic welding is employed for joining copper and aluminum materials.
Additionally, due to copper and aluminum's rapid heat transfer and high reflectivity to lasers, the connecting piece typically has a relatively large thickness. Therefore, employing a higher power laser is necessary to achieve successful welding.
Laser welding has emerged as a standout among various welding methods for several reasons. Firstly, it boasts high energy density, resulting in minimal welding deformation and a small heat-affected zone. This effectively enhances part accuracy, with smooth, impurity-free, uniform, and dense welds, eliminating the need for additional grinding work. Secondly, laser welding offers precise control, with a small focal point and high-precision positioning, facilitating automation with robotic arms. This improves welding efficiency, reduces man-hours, and lowers costs. Furthermore, when welding thin plates or wires, laser welding is less prone to melting back compared to arc welding. It also accommodates a wide range of materials, enabling welding between different materials.
